Water-wave energy has 15 to 20 times more energy per square meter than wind or solar, and oscillating water column (OWC) wave energy conversion systems have the highest potential of all of the conceived energy converters to provide this renewable energy in the form of electric power. It is well known by researchers that the efficiency of the air turbines used in OWC systems can be improved by adjusting the pitch, or the attack-angle, of the turbine blades to best match the air and blade surface velocities, thus increasing the aerodynamic blade lift and rotor torque. All existing variable pitch control systems rely on electric/pneumatic/hydraulic feedback control systems to actuate the blade pitch. However, these conventional approaches are mechanically complex, unreliable, and costly.
During operation of an OWC system, air pressure within an air chamber oscillates with the water waves as they pass through the chamber. The pressure of the air entrapped in the chamber is forced out of the chamber through one or more air turbines as the peak of a wave passes through the chamber, and air is drawn into the chamber, for example, through the same turbine(s), as the trough of a wave passes through the chamber. The magnitude of the pressure and the flow rate of the air is a non-linear function of the amount of potential energy in the incident wave, and these magnitudes are constantly varying with time during the waves' interaction with the OWC structure. The constantly varying pressures within OWC systems make it challenging to optimize their performance.